Constructing the Martin Lewis Little Engines Northern Tender

Carrdo · Post by **Carrdo** » Sun Aug 09, 2015 12:19 pm

The first fitting of the six wheel tender trucks to the tender underframe.

Everything looked good, initially, with even the truck side rollers sitting nicely on the tender underframe bolster beams.

But then, when viewed from the side, the tender underframe sits too high above the trucks for my liking so I need to cut down on the tender underframe bolster beam thickness by up to 1/2" or make a pocket in the tender underframe bolster beam for the truck bolsters to sit down into or a combination of both. I need to think about it a bit.

Carrdo · Post by **Carrdo** » Sun Aug 09, 2015 1:22 pm

Hi Stephane,

Yes, I do need to change this thread title to something like "Constructing the Martin Lewis Little Engines Northern Tender" and was going to but haven't yet...

What can I say about the Hudson copper boiler - it has become a victim just like the 1" scale Atlantic copper boiler which was supposed to be silver soldered two years ago and is still sitting uncompleted.

I do have a a long, long list of locomotive/shop projects to do but I would have to live to 140 just to get most of what is on the list done so am just doing what takes my interest at the moment.

I do have a shop upgrade coming which I didn't want to get into but since there are no commercial shops here which do this anymore (i.e. HSS, carbide T&C grinding), more diversion.

Anyway, I can be a troublemaker as I recently caused Richard to undertake a major shop upgrade of his own concerning his CNC mill which (not intentionally) I demonstrated needed to be much more rigid than it was.

Carrdo · Post by **Carrdo** » Sun Aug 16, 2015 1:53 pm

More aligning, clamping, checking, adjusting if necessary, then drilling and tapping.

Twelve angle brackets have now been installed. For the complete builtup underframe assembly, there are 48 in total.

Just slow, careful and seemingly endless work.

Carrdo · Post by **Carrdo** » Thu Aug 20, 2015 6:20 pm

More heavy milling on the tender underframe bolster beams.

In the end I cut down the total height of the tender underframe bolster beams themselves by about 3/32" and further machined an additional center cutout in the bolster beams by another 3/16" which lowered the entire underframe 9/32" from the height which results if one follows the Lewis prints.

Now there is 1/4" between the top of truck side frames and the bottom of the underframe itself which looks good to me.

The reason why this was done is seen in the last photo of another Little Engines Northern tender. But I really like the tank construction and the riveting on this model and want to duplicate it if ever I get that far.

Carrdo · Post by **Carrdo** » Sat Aug 22, 2015 3:30 pm

We now have a rolling chassis.

Both truck king pins are now connected (as a reamed fit) through to the tender underframe with retaining circlips at each end of the king pins so the trucks cannot separate from the tender when it is lifted.

The trucks do rotate very nicely and can tilt ever so slightly with all parts having a very smooth motion but they will have to be track tested also.

Lots of things still to do on the chassis though.

Carrdo · Post by **Carrdo** » Thu Oct 01, 2015 4:33 pm

A different setup. Further machining operations on the rear sill of the tender underframe so that the rear 6 wheel truck can fully rotate without fouling the inner face of the end sill.

Don't know why but the front and rear trucks are not the same distance from the ends of the tender underframe as the underframe bolster beam centers are shown on the print as having different distances from the ends of the underframe. They don't differ by a lot but they definitely are not the same.

Am starting to collect quite a pile of dull end mills.

Carrdo · Post by **Carrdo** » Fri Dec 04, 2015 8:49 pm

Now the fun starts - to connect all of the internal structural channels on the built up tender underframe.

To do this one needs at least 48 angle brackets and maybe up to 54 of them.

The sequence is first to locate, setup and cut to length the 6 main underframe sub channels which run end to end on the tender underframe.

Then, locate and clamp a particular angle bracket (as shown in the first two photos) after all previous angle brackets/bolster brackets/the external frame brackets have been bolted in place and aligned as we are adding, piece by piece, each bracket to the internal frame assembly which has to be in its final correct (bolted) position before any new piece is added.

Note the external spring caliper and 6" scale with depth stop which are used to determine the channel spacing and the depth of each angle bracket below the top of the frame.

Then, with everything in place, carefully clamp the particular angle bracket. I used two toolmakers clamps to to this. If anything shifts or moves, start over again. It is not as easy as it looks as some of the frame pieces which need to be clamped are tapered.

Then, carefully remove the particular frame piece/angle bracket sub part, being particularly careful not to shift the clamped parts. If this happens one has to start over again.

Setup the part assembly in the vise of the mill and proceed to drill and tap the angle bracket as shown in photos 3 and 4. Quite often, external support in the form of an adjustable parallel is needed as the frame part/angle bracket does not fit well in the vise. Note that all of the angle brackets have previously been machined and the two hole locations center punched as shown in the fourth photo. This is a project by itself.

After drilling and tapping, re-assemble the part assembly and check that all parts can be assembled and are in alignment. Note that all angle brackets need to be marked as to their particular frame location (both the brackets and the frame parts). Think about trying to re-assemble 48-54 brackets if they all looked the same and you didn't know where they went on the frame!!

Repeat the above 48-54 times or until you can't take it anymore. I can only manage to install 4-6 brackets per day.

The last photo shows the number of internal brackets installed to date (with no assembly/disassembly problems).

Carrdo · Post by **Carrdo** » Sat Dec 05, 2015 10:22 pm

A bit more progress.

Carrdo · Post by **Carrdo** » Fri Dec 18, 2015 9:46 pm

The next operation was to fit and attach all of the nine cross channels to the center section longitudinal channels of the tender underframe.

I fit the channels together before adding the angle brackets but you don't have to do it this way.

The first photo shows the setup used to shape each end of a cross channel so that it will fit neatly inside the longitudinal channels. At first, I tried to do this by the by guess and by golly method but that didn't work out too well.

A cross channel was set on a 16 degree sloped support piece in the vise and both the mill's table stop and a vise stop were employed to position the channel and control the length of cut. After each cut on one side of the channel, without changing anything, the channel was then flipped over and the same cut repeated on the other side of the channel. The cut end of the channel was frequently tested against another channel piece as shown in the third photo as the cuts progressed and any need adjustments made to the depth and length of cut.

The two pieces will never quite fit together perfectly as this is hot rolled steel which varies slightly in size and shape, is often warped a bit and has all sorts of minor dipsy doodles along its length.

Post by **Glenn Brooks** » Tue Dec 22, 2015 4:30 pm

Wow. You should rivet the body of the tender out of clear lexan so you can see the craftsmanship of the frame!

Carrdo · Post by **Carrdo** » Tue Dec 22, 2015 4:35 pm

All of the underframe center cross channels formed and ready for installation.

Just ensure the cross channels are securely held for machining. The center cross channels were a bit difficult to hold in the vise of the mill when when set on a slope for milling the tapered ends.

Lots of drilling and tapping still to do but the tender underframe is now starting to look like the Lewis print.

This is going to be a heavy tender (at least for 3/4" scale - but all of you 7.5" gauge subscribers out there can laugh).

Carrdo · Post by **Carrdo** » Mon Dec 28, 2015 6:28 pm

Some further work.

Just producing the angle brackets is a project all on its own. Good lighting is essential when undertaking prick and center punching.

The cross channel angle brackets need to be positioned carefully. And held securely after positioning.

The setup for drilling the angle brackets and after bolting.

The Home Machinist!